Electric heating unit and method of manufacturing the same.



R. W. DAVIS, JR; moms HEATENG mm AND METHOD OF MANUFACTUHlNG THE SAME.

APPLICATION FILED AUG.26, I912.

Patented Jan. 2, 1917.

, of asbestos ance with my invention;

UNITED STATES PATENT OFFICE.

ROBERT WILLIAM DAVIS, JR., OF ASPINWALL, PENNSYLVANIA.

ELECTRIC HEATING UNIT AND METHOD OF MANUFACTURING THE SAME.

" Application filed August 26, 1912.

To (ZZZ whom it may con ern:

Be it known that 1, ROBERT Ninnnuri and Method of Manufacturing the Same,

of which the following is a full, clear, and exact description, reference being bad to the accompanying drawings, forming part of this specification, in which Figure 1 is a perspective view of one form of improved heater made in accordand Fig. 22 is a sectional view through one form of mold, containing one form of heater.

This invention relates to an improvement in electric heating units, and the thod. of making the same. i

The object of the invention is to a device of this character which will be simple and eiiicient, and which can be cheaply and readily manufactured from cheap raw materials, which may readily be obtained.

The precise nature of my invention will be best understoidby reference to the accompanying drawings, which will now be described, it being premised, however, that various changes maygbe made in the details of construction and general arrangement'of the parts, without departing from the spirit and scope of my invention as defined in the appended claims.

In the drawings, the numeral 2 designates the body oi the unit, and 3 the supporting in the form shown in the drawings.

4, 4; .are lead wires extending to the ends oi? the resistance wire 5, which is partially embedded in the body 2. This resistance is provided with a plurality of parallel members connected to each other in series by downwardly extending loops, the upper faces thereof being approximately flush with the upper face of the body, while the loops are embedded in the body of the material to retain the resistance in position with relation thereto.

The body 2 preferably consists of asbestos and cement, which are mixed in. suitable proportions, for example, about one pound to seven pounds of cement, which are thoroughly mixed with water to form a plastic mass.

In the preferred method of manufacturing, I utilize a mold, such as shown in sec tion at 6 in Fig. 5, together with a presser provide Specification of Letters Eatcnt.

Patented Jan. 2, 1917'.

SerialNo.717,042.

plate 7. I first place the wire or bars, which are formed of resistance material, in the mold, and permit the ends to extend therefrom for attaching the leads. I then place suflicient ot' the plastiomass into the mold and temp it around the wires, and then place the presser T in position, and press the material by any well known method, or I may compress it by means of screws 8 presser plate, and. which engage screwthreaded orifices in lugs 10 extending from the mold. After the mass has been pressed to a predetermined degree, it is allowed to remain under pressure in the mold for about twelve to fifteen hours to permit the slab to set. The slab may then be removed from the mold and. an electric current may be intermittently passed through the resist ance for a short time so as not to overload the lead wires, until after the water has been driven out of the slab. In this way the slab may be dried in a few minutes and may be immediately used to heat any suit able obect or material. I

It will be readily understood by those familiar with the art that the slab may be incased in any suitable manner so that any portion or the entire unit may be covered to 'meet the particular requirements for which the unit is to be used. Itwill also be understood that the unit may be reinforced in any desired manner to provide a'unit which has sullicient strength to resist the various stresses and strains to which it would be subjected when in use. It will readily be understood by those familiar with the art that any form of terminal or switch may be used which may be connected to the unit or detachedthere'from; also that insulating talilets or shields may be used in conjunction therewith to protect table tops and the like. These insulating members may be connected to the unit in any desired manner or may be detached therefrom.

The advantages of my invention '-result from the provision of a heat unit which can readily be manufactured, and in which the resistance wires are embedded in a body of asbestos and cement. I

1. An electric heating unit consisting of a molded body formed of asbestos and cement together with electric resistance material of exposed members on the upper extending through lugs 9 on the posed members in series with each other;

substantially as described.

2. An electric heating unit, consisting ofa molded body portion formed of asbestos and." cement and electric resistance material,

said body portion having legs formed into grally therewith, the resistance material having a plurality of parallel members on the upper surface of the body and downwardly extending loop members embedded in the body, said loop members cgnnecting the parallel members in series with each other; substantially as described.

3. The method of manufacturing, hard, elastic and smooth faced electric heating units, which consistsin placing resistance material in the mold, then'placingaplastic mass of asbestos mixed with Water and cement in the mold overthe resistance matcrial, then applying pressure to the mold to compress the plastic mass therein, and retainirig the massunder pressure a sufficient time to permit the mass to change its chemical nature by absorbing chemically hydrous Water, substantially'as described.

4-. The method of manufacturing electric heating units, which consists in first placing the electric resistance material in a mold, then placing a plastic mass of asbestos and cement in themold around the wire, then compressing the plastic mass within the mold, and permitting the article to remain in the mold until set, and then drying the mass by intermittently passing an electric current through the resistance material; substantially as described.

5. An electric heating unit consisting of a body portion having legs integral there with, an electric resistance material having a plurality of members at the surface of the body, and a plurality of loop members connected to said members and embedded in the body arranged to anchor the resistance ma.

terial thereto; substantially as described.

6. An electric heating unit comprising a body portion of asbestos and cement, in combination with a plurality of resistance members at the surface of the body, said resistance members having loops connected thereto and embedded in the body to anchorthe resistance members thereto, said body portion being hard and elastic and having smooth surfaces and sharp edges; substan tially as described.

7. An electric heating unit comprising a body having integral legs formed of asbestos and cement, a plurality of resistance members at the surfaces of the body, and a plurality of loops connected to said resistance members and embedded in. the body, said body portion and legs being hard and elastic and having smooth surfaces.

In testimony whereof, I have hereunto set my hand.

ROBERT iVILLIAM DAVIS, JR.

Witnesses G120. B. Breanne, Jesse B. HELLER. 

